title: Intraocular pressure change over a habitual 24-hour period after changing posture or drinking water and related factors in normal tension glaucoma.
abstract: OBJECTIVE
  We investigated the correlation between 24-hour IOP in the habitual (sitting during day and supine during night) position (H24h-IOP) and IOP after a postural-change test (PCT-IOP) and a water-drinking test (WDT-IOP). We also investigated ocular and systemic factors related with them in patients with normal tension glaucoma (NTG).
  
  
  METHODS
  Japanese NTG patients underwent H24h-IOP, PCT-IOP, and WDT-IOP measurements during a 24-hour period. Correlations among H24h-IOP, PCT-IOP, and WDT-IOP, and contributing ocular/systemic factors were investigated using regression analysis.
  
  
  RESULTS
  There were 33 patients included. Peak H24h-IOP correlated positively with peak PCT-IOP and peak WDT-IOP (estimate = 0.422 and 0.419, P ≤ 0.010), and peak PCT-IOP with WDT-IOP (0.44, P = 0.002). Peak H24h-IOP correlated with refraction (0.36, P = 0.048) and negatively with the mean deviation (MD, -0.066, P = 0.031). MD and baseline IOP (the mean of H24h-IOP) correlated negatively with the H24h-IOP fluctuation (-0.058 and -0.58, P ≤ 0.050). Refraction, baseline IOP, mean blood pressure (mBP), and body mass index (BMI) correlated with peak PCT-IOP (0.23, 0.52, 0.097, and 0.32, respectively, P ≤ 0.038). PCT-IOP difference correlated with refraction and mBP (0.31 and 0.093, P ≤ 0.016) and negatively with age (-0.069, P = 0.003). Central corneal thickness, baseline IOP, age, and BMI correlated with peak WDT-IOP (0.030, 0.40, 0.088, and 0.26, P ≤ 0.050). Age and BMI correlated with WDT-IOP difference (0.086 and 0.20, P < 0.032).
  
  
  CONCLUSIONS
  Positive correlation was found among the peaks of H24h-, PCT-, and WDT-IOP. A worse visual field was associated with higher peak and greater fluctuation of H24h-IOP in NTG. Several ocular/systemic factors were important in interpreting H24h-, PCT-, and WDT-IOP.
authors.affiliation: Department of Ophthalmology, University of Tokyo, Graduate School of Medicine, Tokyo, Japan. reisakata-tky@umin.ac.jp
authors.forename: Rei
authors.initials: R
authors.lastname: Sakata
authors.forename: Makoto
authors.initials: M
authors.lastname: Aihara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Murata
authors.forename: Hitomi
authors.initials: H
authors.lastname: Saito
authors.forename: Aiko
authors.initials: A
authors.lastname: Iwase
authors.forename: Noriko
authors.initials: N
authors.lastname: Yasuda
authors.forename: Makoto
authors.initials: M
authors.lastname: Araie
mesh_terms: D002940:Circadian Rhythm / Q000502:physiology*; D004326:Drinking / Q000502:physiology*; D060766:Drinking Water / Q000008:administration & dosage*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D057066:Low Tension Glaucoma / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D012044:Regression Analysis; D014065:Tonometry, Ocular
chemical_list: D060766:Drinking Water
keywords: generalized estimating equation; habitual 24h-IOP; normal tension glaucoma; postural changing; water drinking